What are tree snorkels?

Ecologist Christian Dunn discusses the snorkel-like roots of the mangrove tree.

Trees with submerged roots develop snorkel-like structures known as pneumatophores © Auscape/ Getty

Trees growing in flooded soils require special adaptations if they are to 
survive this watery habitat. 
One of the problems they face is how to make sure their roots receive sufficient oxygen to function properly.

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In much 
the same way 
that we can 
use snorkels
 to breathe if we
want to keep our
heads underwater,
 trees with submerged
 roots develop specialised root
structures known as pneumatophores.

Brave the waters of a mangrove swamp and you will see these slender, stick-like structures in their thousands, protruding from the soil and shallow water.

Pneumatophores are usually about 30cm in length. They take in oxygen through minuscule pores known as lenticels and transport it down into 
the deeper root system, creating a thin, oxygen-rich layer around the very base of the plant.

Indeed, experiments have revealed that if the pneumatophores are covered, the transportation of oxygen ceases and the mangroves die.

Another adaptation of mangrove trees are stilt roots, or prop roots – pitchfork-like extensions from the trunk that grow downwards into the sediment, helping to stabilise the plants against tides and flooding.

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